1. Field of the Invention
The present invention relates to a data management apparatus using, a data management method, and a recording medium which use a flash memory.
2. Description of the Prior Art
Conventionally, when an electronic apparatus such as a computer is used as a main storage apparatus, a memory apparatus is used to suffice a capacity of this main storage apparatus. As this storage apparatus, there can be exemplified a magnetic tape, magnetic disc, magneto-optical disc, paper tape, memory card, and the like. Among these apparatuses, the memory card is widely used for its comparatively high speed of transfer rate.
Moreover, this memory card is built in a still image pickup apparatus (so-called still camera) and in a camera of a video tape recorder, so as to be used as a storage apparatus for recording a pickup information.
The memory card includes memory means such as a semiconductor integrated circuit embedded in a case made from, for example, a synthetic resin. As the semiconductor integrated circuit, a flash memory (electrically erasable type programmable ROM (read only memory)) or the like is used.
In the memory apparatus such as the aforementioned memory card, a data management is carried out by way of a so-called distributed management method or a collected management method.
The distributed management method is realized as follows. Memory means for storing a data in a storage apparatus is divided into a data erase units such as blocks, and for each of the blocks there is provided a block management information such as a block flag, a logical address, and a linkage information, which are distributed and created for the respective blocks. Hereinafter, such management information items will be referred to as a distributed management information. In the distributed management method, when an electronic apparatus is activated for carrying out a data read-out and/or write-in from/to the aforementioned storage apparatus, firstly, the electronic apparatus collects the distributed management information items distributed in the respective blocks of the storage means and reads them into storage means of the electronic apparatus, so as to create a collected management table which enables to carry out an all-at-once management of the storage means of the storage apparatus, thus carrying out the data of the storage apparatus.
In a case when this distributed management method is used, upon modification of a data in the respective blocks in the storage means of the storage apparatus by a signal transmitted from the electronic apparatus, the distributed management information is also modified. Consequently, each time when the electronic apparatus is activated as has been described above, the latest distributed management information items are collected from the respective blocks of the storage means in the storage apparatus, so as to create a management table in the storage means of the electronic apparatus. That is, according to this distributed management method, for example, even if any of the blocks in the storage means in the storage apparatus is destroyed, upon next activation of the electronic apparatus, the distributed management information items excluding that of the destroyed block are collected, so as to create a collected management table in the storage means of the electronic apparatus. Consequently, in the distributed management method, even if any of the blocks in the storage means of the storage apparatus is destroyed, it is possible to carry out a data write-in and/or data read-out to/from the blocks not destroyed. That is, the distributed management method is comparatively tough against destruction because there will be no such case that write-in and/or read-out cannot be carried out to/from the entire storage means.
However, if the aforementioned distributed management method is applied to a storage apparatus having a large capacity and a plenty of blocks, when activating an electronic apparatus for carrying out a data write-in and/or read-out to/from the storage apparatus, it takes quite a time to create a collected management table in the electronic apparatus. Thus, activation of the electronic apparatus requires a plenty of time, preventing the high-speed processing.
The other method, i.e., the collected management method is realized as follows. The management information items such as a block flag, logical address, and linkage information of respective blocks in storage means of the storage apparatus is stored in a single place in the storage means, and a management information is created for all-at-once management of the data of the respective blocks. Hereinafter, such a management information will be referred to as a collected management information. When the electronic apparatus is activated for carrying out a data read-out and/or write-in from/to the aforementioned storage apparatus, the electronic apparatus reads out the aforementioned collected management information so as to create a collected management table in the storage means of the electronic apparatus, thus carrying out management of the data of the storage apparatus.
In a case when this collected management method is employed, upon activation of an electronic apparatus for a data write-in and/or data read-out to/from the storage apparatus, what is necessary for the electronic apparatus is to read out the collected management information, thus enabling to carry out the activation of the electronic apparatus in a short period of time, which in turn enables to realize a high-speed processing.
However, when carrying out management of a data of a storage apparatus by the aforementioned collected management method, if the collected management information in the storage means of the storage apparatus is destroyed, it becomes impossible to carry out a data write/in and/or read-out to/from the entire storage means. That is, this method is not tough for the data destruction. Moreover, according to the collected management method, each time a data of respective blocks is modified in the storage means of the storage apparatus, the entire collected management information need be modified for data consistency between the collected management information and each of the blocks. In order to rewrite a plenty of blocks, a plenty of time is required for modifying the collected management information, thus preventing a high-speed processing.